Under the system, each Weibo account will begin with a score of 80 and points will be deducted for any perceived misconduct. Accounts that drop to zero will be canceled.

Weibo and rival platforms like Tencent's QQ have become hugely popular in China, with many Chinese regarding them as an important source of news and other information. Weibo is estimated to have 300 million users.

The contract seeks to prevent posts that "spread rumors, disrupt social order, or destroy social stability."

The new rules also seek to stop the use of code words or other expressions often employed by Chinese web users to refer to controversial people or events. For example, the disgraced Chinese politician Bo Xilai was often referred to as BXL.

Doug Young, a Chinese media expert from Fudan University in Shanghai, said the steps are intended to ease Beijing's concerns about the spreading of false rumors.

"I think Sina are trying to be proactive and clean up the site and show the government they are taking steps to stop people from spreading false information or other posts that create trouble," he said.

In April, China's Internet regulator temporarily suspended the comments sections of Weibo and Tencent's QQ as a punishment for allowing rumors to spread.

Authorities also closed 16 websites and detained six people for allegedly spreading rumors of "military vehicles entering Beijing" shortly after the arrest of Bo when China's Internet was rife with talk of an alleged coup.